"A group of volunteers cleaning up the shores of the Mississippi River near the biggest city in Tennessee, have stumbled across the remains of an ancient boat encrusted in mud. A team of acheologists from the University Of Tennessee that was rapidly called to the site, confirmed that the ship was most certainly a Viking knarr..."

As we see, Northern Mississippi is about the same latitude as Northern Morocco, so no problem here. Temperature wise, North America's East coast down to Florida is colder than Africa at the same lattitude, but this fit the Vinkings' tastes better. We also see that they stay close to the ocean, unless we are talking about islands or penisulas. The only exception being the Rus' States were Vikings had strong support from the local population.

Below, a map of the route Vikings used to reach strategic place in Europe and Asia:

As we see, they used the river system to reach body of water across the continent, up to the Caspian Sea. The Mississippi River is a likely place to find Viking evidence, along with the East Coast.

It get's a bit tricky when we look at the numbers from Greenland. It seems at its peek, the settlement had between 2,000 and 10,000 inhabitants, the lower number being more probable, (maybe 4,000 to 5,000 realistically). They could hardly make a second Greenland, let alone a second Iceland worth of settlers. Also, they had only between 1000 to 1300 to do anything, past that Greenland is declining and the Little Ice Age coming slowly. So a few hundred of explorers/settlers is as much as they could afford at any time. If there were settlements in North America outside L'Anse-aux-Meadows, they must have been few and far between.

It also seems to be commercial outposts in Northern Canada, maybe up to half a dozen. They traded for walrus tusks and polar bear hides to cover Greenland expenses. Maybe there's something like that around Mississippi as well.